Generation of thermal strains in carbon fibre-reinforced bismaleimide (PMR-15) composites

The response of aerospace composites to temperature and humidity

“…This causes the thermal expansion coefficients of the plies and the stress free temperature to vary during thermal cycling because these volatiles slowly desorb over a number of themal cycles. As a result the composites exhibit themal cracking (or thermal fatigue) on cooling from each thermal excursion [26]. …”

The use of thermosets in aerospace applications

“…22 However, this demanding processing procedure limits the wider adoption of these polymers and has led to more variation in the quality of the composites thus produced (particularly for thicker components); moreover Pmr-15 has been found to be susceptible to microcracking following thermal spiking. 23 Phenylethynyl-terminated imides (PetIs) are another product of the naSa Langley r&D Center (now produced under licence by UBe Industries Ltd, tokyo). originally developed within the ill-fated HSCt (high speed civil transport) programme, the materials offer low melt viscosity (through the incorporation of an unsymmetrical dianhydride monomer) and high glass transition temperatures (t g = 330 °C for PetI-330 or 365 °C for PetI-365 depending on the monomer).…”